Another shot of severe storms will be in the forecast later tonight as a stout upper level disturbance currently across the Montana vicinity drops rapidly southeast. Thunderstorms will develop across south central Kansas and northwestern OK this afternoon and move southeast this evening forming a complex of thunderstorms producing very large hail and damaging winds. The moderate risk from the SPC has been shifted westward and does not include Tulsa, but a slight risk of severe thunderstorm activity does include most of Eastern OK including the Tulsa metro.
The various operational models are offering different start and end times for this event, and the usually reliable 4KWRF hi resolution data suggests the bulk of the storms will not arrive in Tulsa until around 11pm tonight. After searching the various data, I have decided to mention a window of opportunity from 6pm through 3am Thursday for severe storms across northeastern and eastern OK. I usually have a much higher confidence regarding the timing of a system on the day of the event, but my confidence level is low concerning the start and ending of the event.
The parameters tonight will support very large hail and damaging winds from 60 to 80 mph, but the current data projections would place these higher storm parameters to our west. The tornado threat tonight is not exceptionally high in northeastern OK but it's not zero either. It also appears the slightly higher tornado threat may exist during the early development portion of the event across far northwestern OK. A weak west to east surface boundary may be located across the northern third of the state by later this afternoon and could enhance the surface inflow into discrete thunderstorms before they congeal into storm complex and move rapidly to the southeast.
The system will be sweeping eastward by early tomorrow morning but there may be some scattered showers or storms lingering through the midday period across extreme eastern OK and western Arkansas with highs tomorrow in the mid-70s along with northwest winds in the 10 to 22 mph range.
The remainder of the weekend forecast will be dominated by a northwest upper air flow, which can be a very tricky flow regarding storm chances. We've been watching the extended models closely for the last few days for these periods and both the GFS and EURO have been offering signals for some early morning storms across portions of northern OK and southern Kansas. The latest 00NAM is also suggesting the possibly of some northwest flow activity, and I have included a chance of a few storms for the Friday pm and Saturday morning period, and also the Sunday evening and Monday morning time periods.
Temps this weekend will be moving back into the lower 80s Saturday, the upper 80s Sunday, a and the lower 90s early next week.